16 Aurigae
Triple star system in the constellation Auriga
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16 Aurigae is a triple star[12] system located 340 light years away from the Sun in the northern constellation of Auriga.[2] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.547,[13] and is located about 2/3 of the way from Capella toward Beta Tauri. It also lies in the midst of the Melotte 31 cluster, but is merely a line-of-sight interloper.[6] The system has a relatively high proper motion, advancing across the celestial sphere at the rate of 0.166 arc seconds per annum,[14] and is moving closer to the Earth with a heliocentric radial velocity of â28 km/s.[3]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga[1] |
| Right ascension | 05h 18m 10.576s[2] |
| Declination | +33° 22â² 17.77â³[2] |
| Apparent magnitude (V) | 4.552[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K2.5 IIIb CN-0.5[4] |
| UâB color index | +1.26[5] |
| BâV color index | +1.276[3] |
| Astrometry | |
| Radial velocity (Rv) | â28.44[3] km/s |
| Proper motion (μ) | RA: +28.505±0.713[2] mas/yr Dec.: â158.421±0.504[2] mas/yr |
| Parallax (Ï) | 9.5090±0.5651 mas[2] |
| Distance | 340 ± 20 ly (105 ± 6 pc) |
| Absolute magnitude (MV) | 0.28[1] |
| Orbit[6][7] | |
| Period (P) | 434.16±0.03 d |
| Semi-major axis (a) | 7.24±1.59 mas |
| Eccentricity (e) | 0.1189±0.0026 |
| Inclination (i) | 52.93±9.46° |
| Longitude of the node (Ω) | 56.20±11.65° |
| Periastron epoch (T) | 2,448,348.1172±17.1872 JD |
| Argument of periastron (Ï) (secondary) | 70.1±1.2° |
| Details | |
| 16 Aur A | |
| Mass | 1.30[3] Mâ |
| Radius | 19.86±0.89[8] Râ |
| Luminosity | 127±11[8] Lâ |
| Surface gravity (log g) | 1.87[9] cgs |
| Temperature | 4,264±58[3] K |
| Metallicity [Fe/H] | â0.40[9] dex |
| Rotational velocity (v sin i) | 0.0[10] km/s |
| Age | 5.07[3] Gyr |
| Other designations | |
| 16 Aur, NSV 1909, BD+33°1000, HD 34334, HIP 24727, HR 1726, SAO 57853, PPM 70153, ADS 3872, WDS J05182+3322[11] | |
| Database references | |
| SIMBAD | data |
The primary component is a single-lined spectroscopic binary with an orbital period of 1.19 years and an eccentricity of 0.1189.[6] The visible member is an aging K-type giant star with a stellar classification of K2.5 IIIb CN-0.5;[4] sometimes just given as K3 III. The notation of the former class indicates weak lines of CN in the spectrum.[6] This star is an estimated five[3] billion years old with 1.30[3] times the mass of the Sun. As a consequence of exhausting the hydrogen at its core, it has expanded to 20 times the Sun's radius. The star is radiating 127[8] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,264 K.[3]
A third component is a magnitude 10.6 star at an angular separation of 4.2â³.[12] It shows a common proper motion with the primary and thus is a likely third member of the system.[6]